(processExecAsyncTimer command processOutputOnEnd onEndProcess onOutput onErrorOutput parent) starts
the command asynchronously. The handler onEndProcess is called when the process
terminates. onOutput receives the output from stdout, while onErrorOutput receives
output from stderr. If processOutputOnEnd is True, the remaining output of a terminated
process is processed (calling onOutput). The call returns a triple (send,process,pid):
The send function is used to send input to the stdin pipe of the process. The
process object is returned in process and the process identifier in pid.

Note: The method uses idle event timers to process the output channels. On
many platforms this is uch more thrustworthy and robust than the processExecAsync that
uses threads (which can cause all kinds of portability problems).

deprecated: use processExecAsyncTimed instead (if possible).
(processExecAsync command bufferSize onEndProcess onOutput onErrorOutput parent) starts
the command asynchronously. The handler onEndProcess is called when the process
terminates. onOutput receives the output from stdout, while onErrorOutput receives
output from stderr. The bufferSize determines the intermediate buffer used to
cache the output from those channels. The calls returns a triple (send,process,pid):
The send function is used to send input to the stdin pipe of the process. The
process object is returned in process and the process identifier in pid.

inputStreamGetLine s n reads a line of at most n characters from the
input stream (potentially waiting for input). The function does automatic end-of-line
conversion. If the line ends with \n, an entire line
has been read, otherwise, either the maximum has been reached, or no more
input was available.

Non-blocking IO

inputStreamGetLineNoWait stream n reads a line of at most n characters from the
input stream in a non-blocking way. The function does automatic end-of-line
conversion. If the line ends with \n, an entire line
has been read, otherwise, either the maximum has been reached, or no more
input was available.